Choice B could be correct, since we do see an increase in blood flow between placebo and placebo + Vitamin E. However, the most likely explanation is because Vitamin E is an "effective anti-oxidant" and prevented the oxidation of fatty acids. Since Vitamin E + fatty caid increased blood flow from fatty acid alone group, it is likely that fatty acid oxidaion somehow slowed down the blood flow. In the future, you will likely see problems where you see multiple options that seem correct, but you need to find the "best" answer based on what the passage is directing you towards. While reading the passage, as soon as I saw vitamin E as "effective anti-oxidant," I knew fatty acid oxidation would come into play. This is a skill you'll get better at, as you do more problems and look at problems from different angles.